Whistler waves observed during an in-situ solar type III radio burst

On Dec. 24, 1996, the WIND spacecraft encoun- tered a solar type III source region at 1 AU, as indicated by a characteristic radio signature down to less than the second harmonic of the local electron plasma frequency, the enhance- ment of the electron flux at high energies and the presence of electrostatic noise at the local plasma frequency. During this interval, electromagnetic wave activity was recorded below the electron cyclotron frequency, by the Time Domain Sampler of the WAVES instrument. Analysis suggests that the observed waves are whistler waves, propagating, approximately parallel or antiparallel to the interplanetary magnetic field, in the plasma frame.